Add rounding to volume percentage display

Shows percentage is sometimes lower than actual because float number
is cast to u16 without rounding, so for example 4.99_f64 becomes 4_u16

src/ui/statusbar.rs

@@ -125,7 +125,7 @@ impl View for StatusBar {
 
         let volume = format!(
             " [{}%]",
-            (self.spotify.volume() as f64 / 65535_f64 * 100.0) as u16
+            (self.spotify.volume() as f64 / 65535_f64 * 100.0).round() as u16
         );
 
         printer.with_color(style_bar_bg, |printer| {